1. Field of the Invention
The present invention relates to a speaker which includes a ring-shaped vibrating member, and in particular, relates to a speaker which can prevent decrease of sound pressure and deterioration of sound quality when listening at diagonal front.
2. Description of the Related Art
Speakers respectively utilizing a ring-shaped vibrating member have been disclosed in Japanese Patent Application Laid-open 2006-100879, Japanese Patent Application Laid-open 2009-171475, and U.S. Pat. No. 6,320,972.
The ring-shaped vibrating member is unlikely to cause divisional resonance compared to a circular dome-shaped vibrating member and to cause sound distortion. Accordingly, such a vibrating member is often used for a tweeter which generates sound mainly in a treble range as being formed in relatively small diameter.
Here, in a speaker utilizing a ring-shaped vibrating member, a part of the vibrating member exists respectively at both sides as sandwiching a center line when viewing a sectional view sectioned at a face including the center line. Accordingly, a sound-generating portion is to be located respectively at both sides as sandwiching the center line.
Accordingly, when listening sound from diagonal front being angled against the center line, interference is more likely to occur between a sound wave from a sound-generating portion at one side and a sound wave from a sound-generating portion at the other side as sandwiching the center line.
Since treble sound waves have short wavelength and high directivity, sound pressure is more likely to be decreased and sound quality is more likely to be deteriorated when listening at diagonal front owing to interference between sound waves from the sound-generating portions located at both sides as sandwiching the center line.
In particular, in a speaker system for automobile use, tweeters are often attached at diagonal front positions from an occupant (e.g., pillar portions at both sides of a front window). Accordingly, influence due to the abovementioned sound wave interference is apt to be obtrusive.